Studies on Meson Spectroscopy --- Search for Exotic States

GAMS合作旨在寻找由中心碰撞和pip和pp相互作用的电荷交换过程产生的新介子态。它由两部分组成，一是在第六次IHEP和CERN联合实验计划框架下，利用70 GeV质子同步加速器和GAMS 47pi光谱仪产生的32 GeV质子的实验项目SERP-E-172，另一部分是利用超级质子同步加速器产生的300 GeV质子和450 GeV质子的实验项目NA12/2。以及欧洲核子研究中心的GAMS 4000光谱仪。GAMS是探测反应中产生的中性介子态衰变的高能伽马射线的能量和位置的光谱仪的昵称。KEK小组于1998年加入合作，并继续工作。同时，KEK和IHEP在1990年签署了GAMS实验的科学合作协议。在1991年5月至9月间，利用欧洲核子研究中心（CERN）升级后的GAMS 4000光谱仪系统进行了96个有效日的实验运行，收集了中央碰撞产生的8000万次触发事件。在运行期间，我们测试了欧洲核子研究中心和KEK小组开发的新的数据采集系统，该系统将在1992年的下一个运行中安装。在IHEP上，我们用32个GeV负介子和GAMS 4pi光谱仪进行了30有效天的数据采集。我们升级了它，通过安装大型漂移室来探测介子态衰变的带电粒子。它们的信号读出系统是由KEK集团研制的。目前正在对数据进行部分波分析。同时，我们分析了1984-1987年在pip电荷交换过程中产生的etaeta'和omegapi^0系统数据。X（1910）在etaeta的最终状态中被发现。这个国家有望成为一个充满异国情调的国家。X（2200）在omegapi^0的最终状态也被发现。它与p（770）具有相同的量子数，被认为是p（770）的径向和轨道激发。这些分析结果已在hadron91会议上报告，并已提交出版

The GAMS Collaboration aims at searching for new meson states produced by the central collisions and the charge exchange process of pip and pp interactions. It consists of the two parts, i. e. one is the experiment, SERP-E-172 which uses 32 GeV pions produced by the 70 GeV Proton Synchrotron and the GAMS 47pi Spectrometer at IHEP (Protvino, Russia) in the framework of the sixth IHEP and CERN joint experiment programs and the other is the Experimental project, NA12/2 which uses 300 GeV pions and 450 GeV protons produced by the Super Proton Synchrotron. and the GAMS 4000 spectrometer at CERN. GAMS is a nickname of the spectrometer which detects energy and position of high energy gamma-rays decaying from neutral meson states produced in the reactions.The KEK group joined the collaboration in 1998 and have continued the work. Meanwhile, the agreement between KEK and IHEP have been signed up on the scientific collaboration for the GAMS experiment in 1990.We performed the experimental runnin … More g of 96 effective days between May and September in 1991 with the upgraded spectrometer system of GAMS 4000 at CERN and collected 80 millions of triggered events on the central collision production. During the run, we tested the new data acquisition system which has been developed by CERN and KEK groups and will be instaled in the next run of 1992. At IHEP, we performed the data taking run of 30 effective days with 32 GeV negative pions and the GAMS 4pi spectrometer. We have upgraded it for detecting charged particles decaying from meson states by installing large drift chambers. The readout system of signals of them has been developed and prepared by the KEK group. Partial wave analyses of the data are now under way.Meanwhile, we have analyzed etaeta' and omegapi^0 system of 1984-1987 data produced in the pip charge exchange processes. X (1910) has been found in the etaeta' final state. The state is expected to be a qq exotic one. X (2200) in the omegapi^0 final state has also been found. It has the same quantum numbers that of p (770) and is considered to be a radial and orbital excitation of p (770). These results of the analyses have been reported at fhe conference, Hadron9l and have been submitted for publication Less